Contactless Card Power Management via Dynamic Circuit Switching
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Solution Overview
Problem
Existing methods for managing power supply in electronic devices without an internal power source, such as contactless cards, are inefficient in optimizing energy use and managing power consumption, particularly when interacting with external electromagnetic fields.
Innovation Solution
A method involving a secure electronic circuit that sends a time extension request to a reader device, evaluates the available power from the electromagnetic field, and adapts the power supply to the card's elements, including a microcontroller and fingerprint sensor, by switching between power sources and modes to optimize energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the card activates multiple circuits simultaneously, then more functions are available, but power consumption exceeds available energy from the electromagnetic field
Solution Approach 1:
The card dynamically adjusts its power consumption by selectively activating circuits based on available power. The secure element evaluates the electromagnetic field strength and controls switching elements to activate or deactivate specific circuits (e.g., microcontroller, fingerprint sensor) according to real-time power availability, transforming a static power consumption system into a dynamic one that adapts to energy constraints
Solution Approach 2:
The system changes operational parameters by modifying which circuits are active based on power evaluation results. The secure element alters the operational state of various circuits by controlling switching elements, effectively changing the system's configuration from having all circuits potentially active to having only necessary circuits activated based on available energy
2Measurement precision
If the card requests time extension to evaluate power, then power management accuracy improves, but communication time with the reader increases
Solution Approach 1:
The card performs power evaluation during the time extension period that is already allocated for communication. By utilizing this extended time window to evaluate available power from the electromagnetic field before activating circuits, the system prepares in advance with accurate power information without adding extra communication rounds, thus achieving preliminary action within existing time constraints
3Adaptability or versatility
If the card activates high-power circuits, then more functionality is available, but the electromagnetic field strength required increases
Solution Approach 1:
The system dynamically matches circuit activation to available electromagnetic field strength. The secure element evaluates the field strength and selectively activates circuits whose power requirements are met by the available energy, preventing activation of high-power circuits when field strength is insufficient, thus adapting functionality to environmental energy availability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures reliable and efficient power management, allowing the card to maintain optimal operation while minimizing energy consumption and noise during communication, ensuring backward compatibility with existing readers.
Implementation Method 1
evaluating, during the time extension, a power available from an electromagnetic field radiated by the second device
Implementation Method 2
adapting the power supply to the second element and to the first element(s) according to the available power
Data Source
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AI summary
This description relates to a method for managing the power supply of one or more first elements by a second element of the same first device, comprising the steps of: sending a time extension request (WTX) to a second device; evaluating, during the time extension, the power available from an electromagnetic field radiated by the second device; and adapting the power supply of the second element and the first element(s) according to the available power.